1. Field of the Invention
The present invention relates to a device and method for determining gas evolution rates in solids and liquids, and, more particularly, to such a device and method for determining carbon dioxide evolution rates in a sample.
2. Description of Related Art
Respiration is a common indicator of biological activity. Respirometry, the measurement of respiration rates, has been applied to a broad spectrum of applied and environmental microbiology, such as toxicity, with treatability, process control, and prediction of biological oxygen demand (BOD5) in wastewater treatment, assessment of metal toxicity, living soil microbial biomass, and food quality.
Respiration rates can be measured either by rates of oxygen consumption or CO2 evolution. Rapid oxygen consumption rate can be measured by using an oxygen probe or a quantitative electrolytic cell. Most oxygen respirometers, however, are applicable only to liquid samples. Oxygen respirometers with an electrolytic cell can be used to determine respiration of solid or semisolid samples, but their sensitivity is compromised.
Sensitive and rapid CO2 respirometers based on infrared (ir) detectors have been developed in the past three decades and can handle solid samples with high speed and sensitivity. Instrumental respirometers are technically complicated and expensive if accuracy and sensitivity are needed. Noninstrumental CO2 respirometers operated by an alkaline trap and acid-base titration have been in existence for many years. They are simple but relatively slow, with a measurement time in days, and less sensitive, with a detection limit in mL CO2/day. Sensitive and rapid determination of respiration rates is highly desirable in monitoring microbial activity in food and environmental samples. A desired sensitivity, for example, would comprise one in the microliter CO2 per hour level, and a rapidity of determination within about an hour.